7. Reverse Integer
Given a 32-bit signed integer, reverse digits of an integer.
Example 1:
Input: 123
Output: 321
Example 2:
Input: -123
Output: -321
Example 3:
Input: 120
Output: 21
Note:
Assume we are dealing with an environment which could only store integers within the 32-bit signed integer range: [−231 , 231 − 1]. For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.
Solution
class Solution {
public:
int reverse(int x) {
int val=0;
while(x!=0)
{
int pop = x%10;
x /= 10;
if( val > INT_MAX/10 || (val == INT_MAX/10 && pop > 7) ) return 0;
if( val < INT_MIN/10 || (val == INT_MIN/10 && pop < -8)) return 0;
val = val*10 + pop;
}
return val;
}
};
解题思路
这道题考察点主要在 字符串反转后整型数是否溢出,需要判断是否溢出。